This invention relates to the field of refrigeration apparatus incorporating energy-saving atmospheric pressure actuated compressor improvements.
Continuing increases in the cost of fossil fuel-derived energy, especially the higher rates of cost increase which commenced in the mid 1970's, has focused commercial attention on a variety of energy-conserving and energy-generating technologies which were previously difficult to justify economically. Included in such energy-conserving concepts is the addition of super-insulation to buildings and heat-operating appliances such as water heaters, cooking ranges and refrigerating equipment. Energy-capturing measures based on geothermal and solar heat have also increased in commercial viability during this period. The now-popular practice of labelling an energy-consuming appliance in terms of its long-term energy consumption and an energy efficiency factor clearly reflects an increased concern for the cost of operating large energy consumption equipment such as the refrigeration machines for air conditioning and food storage.
Although improved insulation and improved electrical to mechanical transfer efficiency in refrigeration machines can significantly decrease the long term operating cost of such equipment, such improvements fall short of enhancing the underlying thermodynamic cycle of such equipment. Improvements which relate to this underlying thermodynamic cycle are nevertheless contemplated by the present invention. The present invention is moreover compatible in spirit with modern arrangements which employ solar energy or other naturally-occurring energy forms to supplement the energy derived from a fossil fuel source in a working apparatus. In the present invention the naturally-occurring energy is derived from atmopsheric pressure.
The patent art includes several examples of thermodynamic cycle apparatus employing unusual compression arrangements. Included in this art is the U.S. patent of Bill L. Pierce, U.S. Pat. No. 4,120,172, which concerns a heat transport system principally intended for use in a small, high-reliability apparatus such as a nuclear-powered artificial heart. In the Pierce apparatus a pressurizer vessel serves as a pneumatic spring between vaporizer and condenser elements of a heat transport system. The pressure vessel's compressor action contemplates the use of a diaphragm located between a pressure chamber and the vaporizer-condenser communicated compression chamber. In one arrangement of the Pierce apparatus, the pressurizer volume is increased to infinity by opening the pressure chamber to the atmosphere and employing a vertical stem pipe and atmospheric pressure as a portion of the pressurizer apparatus. The Pierce apparatus contemplates the use of methanol or acetone as the working fluid and achieves heat transfer between a heat source operating at 150.degree. F. and a heat sink operating at 140.degree. F. or alternately, a source operated at 120.degree. and a sink at 105.degree. F.; these heat transfers are achieved in the nucleate boiling mode of operation.
The patent of Lawrence L. Midolo, U.S. Pat. No. 4,211,093, is also included in the refrigeration art. The Midolo patent concerns a vapor cycle cooling system which employs a rotary vane compressor having two stages and two levels of working fluid compression and arranged such that the output of the lower pressure compressor stage is received into the input of the higher pressure stage. The Midolo apparatus also contemplates the use of an output flow from one expansion valve to cool the input flow of a second expansion valve.
The patent of David A. Snyder, U.S. Pat. No. 4,369,633, is concerned with a multiple-stage compressor having a flash gas injection arrangement wherein gases of two different pressures can be compressed simultaneously. The Snyder invention uses two separate compression chambers in order to utilize a vapor fraction of partially-expanded refrigeration fluid to add the high-pressure gas in the system condenser coil. The Snyder patent also identifies several previous patents concerned with refrigerant compressors having multiple compression chambers.